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Simplified consent in cluster randomised trials: the new EU Clinical Trials Regulation does not provide sufficient guidance

BMJ 2023; 382 doi: (Published 13 September 2023) Cite this as: BMJ 2023;382:e075773
  1. Cory E Goldstein, postdoctoral fellow12,
  2. Rieke van der Graaf, associate professor3
  1. 1Clinical Epidemiology Programme, Ottawa Hospital Research Institute, Ottawa ON, Canada
  2. 2School of Epidemiology and Public Health, University of Ottawa, Ottawa ON, Canada
  3. 3Julius Center, Department of Bioethics and Health Humanities, University Medical Center Utrecht, Netherlands
  1. Correspondence to: C E Goldstein cogoldstein{at}

Cory Goldstein and Rieke van der Graaf argue that the new EU Clinical Trials Regulation on informed consent in cluster randomised trials is ambiguous and could lead to an overuse of opt-out consent approaches that provide inadequate protections for research participants

Key messages

  • The new European Union Clinical Trials Regulation requires the use of “simplified consent” for all cluster randomised trials, but how to interpret this is unclear

  • The ambiguity of simplified consent can push ethics committees towards inappropriately promoting and approving opt-out consent approaches in cluster randomised trials evaluating medicinal products

  • The criteria for an ethics committee to grant simplified consent must be clarified to ensure appropriate ethical protections are afforded to research participants in cluster randomised trials

The new European Union (EU) Clinical Trials Regulation 536/2014 is designed to streamline and harmonise the submission and review process for clinical trials conducted in EU member states and countries in the European Economic Area.1 Since 31 January 2023, clinical trial applications in the EU must be submitted through the Clinical Trials Information System and must abide by the regulation.2

This includes applications to conduct cluster randomised trials (CRTs), which are commonly used for the evaluation of public health, health policy, and health system interventions.3 In contrast to individually randomised trials in which people are randomly allocated to receive study interventions, in CRTs intact groups (such as geographical areas or clinics) are randomly assigned to receive the study interventions. Study interventions can be delivered to the entire cluster as a unit (such as a mass media smoking cessation campaign on the radio) or to professionals in each cluster (such as educational workshops for health providers to improve hand hygiene), but only CRTs that evaluate medicinal products delivered to patients in each cluster fall under the purview of the EU Clinical …

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